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Comprehensive technical documentation covering: - Hardware: OCS/ECS/AGA custom chip registers, Copper & Blitter deep dives - Boot sequence: cold boot through startup-sequence - Binary format: HUNK executable spec, relocation, debug info - Linking & ABI: .fd files, LVO tables, register calling conventions - Exec kernel: tasks, interrupts, memory, signals, semaphores - AmigaDOS: file I/O, FFS/OFS layout, CLI/Shell scripting - Graphics: planar bitmaps, Copper programming, HAM/EHB modes - Intuition: screens, windows, IDCMP, BOOPSI - Devices: trackdisk, SCSI, serial, timer, audio, keyboard - Libraries: utility, expansion, IFFParse, locale, ARexx - Networking: bsdsocket API, SANA-II, TCP/IP stack comparison - Toolchain: GCC, vasm/vlink, SAS/C, NDK, debugging - Reverse engineering: IDA/Ghidra setup, compiler fingerprints, case studies - CPU & MMU: 68040/060 emulation libs, PMMU, cache management - Driver development: SANA-II, Picasso96/RTG, AHI audio All files include breadcrumb navigation. No local paths or proprietary content. |
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|---|---|---|
| .. | ||
| aga_blitter.md | ||
| aga_copper.md | ||
| aga_display_modes.md | ||
| aga_palette.md | ||
| aga_registers_delta.md | ||
| chipset_aga.md | ||
| cpu_030_040.md | ||
| gayle_ide_a1200.md | ||
| README.md | ||
AGA Chipset — A1200 / A4000 / CD32
Overview
The Advanced Graphics Architecture (AGA) is the final custom chipset developed by Commodore, shipping from 1992. It dramatically expands colour depth, palette size, sprite capabilities, and blitter bandwidth while retaining full OCS/ECS backward compatibility.
Chip Summary
| Chip | Name | Changes from ECS |
|---|---|---|
| Alice | MOS 8374 | Super Agnus successor: 64-bit bus, FMODE register |
| Lisa | (unnamed MOS) | ECS Denise successor: 8-bit palette, 256 colours |
| Paula | MOS 8364 | Unchanged from OCS/ECS |
Contents
| File | Topic |
|---|---|
| chipset_aga.md | Alice and Lisa internals, AGA architecture |
| aga_registers_delta.md | New/changed registers vs ECS |
| aga_palette.md | 24-bit colour system, 256 registers |
| aga_display_modes.md | HAM8, 256-colour, doublescan, VGA |
| aga_blitter.md | 64-bit blitter bus, FMODE |
| cpu_030_040.md | 68030/040 on A3000/A4000: cache, MMU, FPU |
| gayle_ide_a1200.md | A1200 Gayle: IDE and PCMCIA specifics |
AGA vs ECS — Key Differences
| Feature | ECS | AGA |
|---|---|---|
| Colour registers | 32 (12-bit) | 256 (24-bit) |
| Max simultaneous colours | 64 EHB / HAM | 256 (or HAM8: 262,144) |
| Blitter bus | 16-bit | 64-bit (FMODE) |
| Sprite width | 16 px | 64 px |
| Sprite colours | 3+transparent | 15+transparent (64-colour attached) |
| Bitplane depth | 6 planes max | 8 planes |
| Palette select | 1 bank | 4 bitplane banks, 4 sprite banks |
Identifying AGA at Runtime
#include <graphics/gfxbase.h>
extern struct GfxBase *GfxBase;
BOOL is_aga = (GfxBase->ChipRevBits0 & (1 << GFXB_AA_ALICE)) != 0;
| ChipRevBits0 bit | Flag | Meaning |
|---|---|---|
| 4 | GFXB_AA_ALICE |
AGA Alice present |
| 5 | GFXB_AA_LISA |
AGA Lisa present |
AGA Machines
| Model | CPU | Notes |
|---|---|---|
| A1200 | 68020 14 MHz | Budget AGA; Gayle IDE; PCMCIA; 2 MB Chip |
| A4000 | 68030/040 25 MHz | High-end; Zorro III; IDE; 2 MB Chip + Fast |
| A4000T | 68040/060 | Tower variant; SCSI |
| CD32 | 68020 14 MHz | Game console; CD-ROM; SX-1 expansion |
References
- ADCD 2.1 Hardware Manual — AGA chapters
- NDK39:
graphics/gfxbase.h,hardware/custom.h - Commodore A1200/A4000 Technical Reference Manuals (local archive)